Abstract

The measurement system for earth gravity acceleration by using mathematical swing pendulum with the light sensor and laser functioned as light source based of
microcontroller (AT89S51) has been fabrication.
In the applied system, the pendulum was stimulated to deviate by swinging it. While laser is halted by the pendulum it is causing really contact from normally change
to normally close. The process is functioned as input data on microcontroller which then processed and sent serially to activate counter and timer. From the process it was yielded value of period that was counted for time of the pendulum swing to definite vibration. The vibration is repeated movement periodically. After calculated by inputting into equation using Delphi language programming, the result was displayed on computer. Such device has realized by using vibration for 5 times with strap cord 0.42 m with yielded period 1.29 second and earth gravity acceleration as 9.89 m/s2.